U.S. patent number 6,116,874 [Application Number 09/120,297] was granted by the patent office on 2000-09-12 for gas compressors.
This patent grant is currently assigned to Knorr-Bremse Systems for Commercial Vehicles Limited. Invention is credited to Gary Peter Brown, Jeremy James Durrant, John McCouch, Toby James Nation, Martin Selway.
United States Patent |
6,116,874 |
Nation , et al. |
September 12, 2000 |
Gas compressors
Abstract
In a piston and cylinder gas compressor having a cylinder block,
a valve plate and a cylinder head the sealing means between the
cylinder head and the valve plate is designed to constrain the
delivered air and/or coolant fluid to flow in an extended fluid
flow path to enhance the heat flow from the delivered air before
arrival at a delivery port.
Inventors: |
Nation; Toby James (Warmley,
GB), Brown; Gary Peter (Kingswood, GB),
Selway; Martin (Steyning, GB), McCouch; John
(Bradley Stoke, GB), Durrant; Jeremy James (Longwell
Green, GB) |
Assignee: |
Knorr-Bremse Systems for Commercial
Vehicles Limited (Bristol, GB)
|
Family
ID: |
27451682 |
Appl.
No.: |
09/120,297 |
Filed: |
July 22, 1998 |
Foreign Application Priority Data
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Jul 26, 1997 [GB] |
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9715741 |
Jul 26, 1997 [GB] |
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9715743 |
Jul 26, 1997 [GB] |
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9715745 |
Apr 6, 1998 [GB] |
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9807236 |
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Current U.S.
Class: |
417/571;
137/512 |
Current CPC
Class: |
F04B
39/064 (20130101); Y10T 137/7838 (20150401) |
Current International
Class: |
F04B
39/06 (20060101); F04B 039/10 (); F12K
015/00 () |
Field of
Search: |
;417/571,569,559,524
;137/512.15,512,512.1,858 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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372 154 B1 |
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Jun 1990 |
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EP |
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494590A1 |
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Jul 1992 |
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EP |
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571 715 A1 |
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Dec 1993 |
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EP |
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705 977 A1 |
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Jun 1996 |
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EP |
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7200686 |
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0000 |
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DE |
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1 129 784 |
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DE |
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1142478 |
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DE |
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6946784 |
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1957668 |
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2410705 |
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2733089 |
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3305791 A1 |
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3813539C2 |
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3909531A1 |
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3940099A1 |
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4125123A1 |
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19535079 |
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Apr 1996 |
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DE |
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59-208181 |
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Nov 1984 |
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JP |
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992232 |
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Mar 1962 |
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GB |
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1132506 |
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Nov 1968 |
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GB |
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1409589 |
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Oct 1975 |
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GB |
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2018364 |
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Oct 1979 |
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GB |
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2044365 |
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Oct 1980 |
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GB |
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2083566 |
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Mar 1982 |
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GB |
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2 165 317 |
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Apr 1986 |
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GB |
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2171465 |
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Aug 1986 |
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GB |
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2208 180 |
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Mar 1989 |
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GB |
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2319569 |
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May 1998 |
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GB |
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Primary Examiner: Walberg; Teresa
Assistant Examiner: Robinson; Daniel
Attorney, Agent or Firm: Barnes & Thornburg
Claims
What is claimed is:
1. A piston and cylinder gas compressor including a valve plate
located between a cylinder and a cylinder head, said cylinder head
having an inlet and a delivery port and said valve plate having
induction and delivery passages with respective induction and
delivery valve means operable to close the delivery passage during
gas induction strokes of the piston and to close the induction
passage during gas delivery strokes, the compressor including first
sealing means providing sealing between the valve plate and the
cylinder and second sealing means providing sealing between the
valve plate and the cylinder head and being characterized in that
the second sealing means incorporates a third means which provides
an extended flow path for the flow of compresses gas from the
delivery passage generally alone the valve plate below the third
means before passing into the cylinder head and generally along the
cylinder head above the third means to the delivery port and the
flow path above and/or below the third means is a generally
U-shaped flow path.
2. A compressor as claimed in claim 1, characterised in that
regions of said U-shaped flow path extend along opposed sides of an
induction gas flow region.
3. A compressor as claimed in claim 2 characterised in that the
said second sealing means comprises a flat gasket and said delivery
valve means are accommodated in a recess of the valve plate.
4. A compressor as claimed in claim 2, characterised in that said
second sealing means comprises a gasket with a three-dimensionally
shaped region which projects into a delivery region of the cylinder
head.
5. A compressor as claimed in claim 1 characterised in that the
said second sealing means comprises a flat gasket and said delivery
valve means are accommodated in a recess of the valve plate.
6. A compressor as claimed in claim 1 characterised in the said
second sealing means comprises a gasket with a three-dimensionally
shaped region which projects into a delivery region of the cylinder
head.
7. A liquid cooled compressor as claimed in claim 1 characterised
in the said second sealing means has a gasket and said valve plate
has recesses which cooperate with apertures of the gasket to
provide an extended flow path for coolant liquid.
8. A liquid cooled gas compressor as claimed in claim 1
characterised in that said sealing means is a gasket with a
three-dimensionally shaped region which projects into a coolant
flow region of the cylinder head which cooperates therewith to
provide extended flow passage for coolant liquid.
9. A piston and cylinder gas compressor including a valve plate
located between a cylinder and a cylinder head, said cylinder head
having an inlet and a delivery port and said valve plate having
induction and delivery passages with respective induction and
delivery valve means operable to close the delivery passage during
gas induction strokes of the piston and to close the induction
passage during gas delivery strokes, the compressor including first
sealing means providing sealing between the valve plate and the
cylinder and second sealing means providing sealing between the
valve plate and the cylinder head and being characterized in that
the second sealing means incorporates a third means which
cooperates with the valve plate and/or the cylinder head to
provided an extended flow path for the flow of liquid coolant from
a liquid inflow port to a liquid outflow port.
10. A liquid cooled compressor as claimed in claim 9 characterised
in that said second sealing means has a gasket and said valve plate
has recesses which cooperate with apertures of the gasket to
provide an extended flow path for coolant liquid.
11. A liquid cooled gas compressor as claimed in claim 9
characterised in that said second sealing means is a gasket with a
three-dimensionally shaped region which projects into a coolant
flow region of the cylinder head which cooperates therewith to
provide extended flow passage for coolant liquid.
12. A compressor as claimed in claim 9 characterized in that said
flow path continues generally along the cylinder head above the
third means before reaching the delivery port.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to gas compressors and relates more
especially to a piston and cylinder compressor.
Piston and cylinder compressors are known which include a valve
plate located between a cylinder and a cylinder head said cylinder
head having an inlet port and a delivery port and said valve plate
having induction and delivery passages with respective valves
operable to close the delivery passage during gas induction strokes
of the piston and to close the induction passage during gas
delivery strokes, the compressor including first sealing means
providing sealing between the valve plate and the cylinder and
second sealing means providing sealing between the valve plate and
the cylinder head.
The object of the present invention is to provide a piston and
cylinder compressor which has improved cooling of delivered
compressed gas.
According to the present invention there is provided a piston and
cylinder gas compressor including a valve plate located between the
cylinder and a cylinder head said cylinder head having an inlet
port and a delivery port and said valve plate having induction and
delivery passages with respective valve means operable to close the
delivery passage during gas induction strokes of the piston and to
close the induction passage during gas delivery strokes, the
compressor including first means providing sealing between the
valve plate and the cylinder and second means providing sealing
between the valve plate and the cylinder head and being
characterised in that the second sealing means incorporates means
which provides an extended flow path for the flow of compressed gas
from the delivery passage to the delivery port and/or for the flow
of liquid coolant between a liquid inflow port and a liquid outflow
port.
In order that the invention may be more clearly understood and
readily carried into effect the same will be further described by
way of examples with reference to the accompanying drawings
with.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a schematic fragmental sectional view of a twin
cylinder air cooled compressor.
FIG. 2 illustrates in three-dimensional manner a cylinder head and
valve plate components of a liquid cooled twin cylinder
compressor.
FIG. 3 illustrates the under-side of the valve plate of FIG. 2
FIG. 3a is a plan view of an inlet valve reed
FIG. 4 illustrates an exploded view of parts of another embodiment
of a single cylinder compressor and
FIG. 5 illustrates an exploded view of parts of another embodiment
of a single cylinder compressor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 an air compressor includes a crankcase and
cylinder body 1 having two cylinder bores 2 and 3 within which
respective pistons 21,22 are operable by a crankshaft (not shown)
to cyclically induce and compress air drawn into compression
chambers 4 and 5. The upper end of the cylinder body is sealingly
closed by a valve plate and first sealing means comprising a gasket
7. The valve plate 7 carries inlet reed-valves (not shown) for both
cylinders. A recess 22 of the upper side of the valve plate
accommodates delivery reed valves 8 and 9 having retaining bridges
represented at 8a and 9a which cover delivery passages 10 and 11
from the respective cylinders for air flow into the delivery air
chamber 12 and common delivery port 13 in the cylinder head 14. The
cylinder head 14 is of good thermally conductive aluminium or alloy
thereof and has internal air cooling fins 15 and adjacent liquid
coolant galleries 16 for conveying heat away from the head. Between
the cylinder head 14 and the valve plate a second sealing means
comprises two gaskets 17 and 18 together with an additional plate
19 between them and an aperture 20 at a position remote from the
delivery port 13.
In operation of the compressor, the pistons 21 and 22 reciprocate
to alternatively compress induced air in chambers 4 and 5 and by
virtue of the additional plate 19 and the aperture 20 thereof
compressed air delivered via reed valves 8 and 9 is drawn across
the underside of the plate 19, through aperture 20 and is
additionally cooled by fins 15 before reaching the delivery port
13. The delivered compressed air at port 13 is therefore cooler
than would be the case if the second sealing means comprising 17,
18 and 19 permitted such air to be delivered more directly from the
delivery reed valves to the delivery port.
Referring to FIG. 2 components of the compressor shown therein in
three dimensions comprise a water cooled cylinder head 41 of a twin
cylinder compressor, a cylinder head gasket 42 and valve plate 43.
The cylinder head 41 and the valve plate 43 are manufactured as
aluminium castings and the gasket 42 is of a suitably elastomer
coated ferrous metal. An under-side plan view of the valve plate is
shown in FIG. 3 from which it is observed that the valve plate has
six cylinder head clamping bolt holes 45, four valved air inflow
passages 46 for each cylinder of the compressor and three air
delivery flow passages 47. Respective flat springy metal inlet
valve reeds, one such being shown in FIG. 3a, are accommodated in
recesses 47 with locating pegs 47a, the configuration being similar
to that described in the Specification of U.K. Patent Application
No. 9715741.6 (K-621). Moreover these respective reeds also have
apertures which provide direct communication from holes 48 of the
valve plate which house unloader valves (not shown) for the
respective compressor cylinders, as described more especially in
the Specification of European Patent No. 0240278.
Reverting to FIG. 2 the top side of the valve plate has a plurality
of recesses. The respective delivery reed valves are captive
beneath reed bridges 49a, these reeds permitting one-way air flow
into a U-shaped delivery air gallery 50 formed by a recess which
has adjoining regions on either side of an inlet air gallery 51
above apertures 46. The valve plate also has four distinct channels
52 formed by recesses through which coolant is arranged to flow via
the gasket 42 from the cylinder head.
The gasket 42 is provided with opposed sealing surfaces for sealing
in known manner between the valve plate and the cylinder head and
is provided with apertures not merely to permit induction and
delivery air flow directly to or from the respective reed valves
but the gasket is provided with selectively positioned apertures
which result in extended flow paths for delivered compressed air.
Such extended flow passages are also provided for the flow of
cooling water through the cylinder head and the valve plate 43.
Referring to the cylinder head 41, a generally centrally positioned
elongate chamber 51a has an inlet port (not shown) and joins via
the gasket 42 with the chamber 51 of the valve plate 43. Unloader
valve ports such as 48a also communicate with the chamber 51a in
operation. Similarly to 50 of the valve plate, a generally U-shaped
air delivery chamber 50a is defined above the chamber 50 of the
valve plate communication between 50 and 50a being restricted to
flow via an aperture 54 of the gasket. The chamber 50a has a
plurality of downward projecting internal cooling fins such as 55
over which delivery air flows before reaching the delivery port
56.
In operation of the compressor, air is drawn into the respective
cylinders in turn via the inlet valve reeds in gallery 50 during
respective induction strokes and driven outwards in turn via the
delivery reed valves past the bridges 49a. The flow path for such
air under compression is constrained by the gasket 42 to follow an
extended flow path from the delivery valves as indicated by the
broken line and denoted A.B,C,D,E,F. This passes from the delivery
valves at A through the generally U-shaped path in chamber 50,
namely beneath the gasket 47, from whence it passes via aperture 54
therein to return along the generally U-shaped path provided in
chamber 51a, namely above the gasket, and past fins 55 to F at the
delivery port 56. cooling of the delivered air is thereby optimized
by such an extended delivery flow path having a U-shaped
configuration both below and above the second cooling means
comprising gasket 42.
Cooling of the cylinder head is also advantageously provided in
enhanced manner by pumped liquid coolant, preferably frost
protected water and inhibitor, which enters the head at coolant
inlet port 57 and follows an arrowed flow path a, b, c, d, e, f, g,
h, i, j to the coolant outlet port (not shown). By selective
provision of coolant flow apertures of the gasket and of distinct
channels or recesses 52 of the valve plate the coolant is
constrained to flow via such circuitous path which avoids
short-cuts and optimises the thermal transfer form the cylinder
head per liter flow rate.
In the embodiments of air cooled or water cooled gas compressors
described in the foregoing in FIG. 1 and FIG. 2, gas delivery valve
reeds are accommodated in recesses provided in the upper surface of
a valve plate whereby the second sealing means, namely the second
sealing means, between the valve plate is designed to restrict the
flow of delivered air and or coolant water in such a way as to
extend the respective flow paths. If such recesses are reduced in
depth or eliminated such that in the limit the valve plate has an
entirely flat upper surface, the second cooling means may be formed
with upwardly projecting regions which extend sufficiently into the
cylinder head to accommodate the or each delivery valve reed
assembly and also provide advantageous extended fluid delivery flow
paths. The embodiments of FIG. 4 and FIG. 5 of liquid single
cylinder compressors in accordance with the invention employs this
concept.
Referring to FIG. 4, the cylinder denoted by reference 61 has
cooling fins 63 and a top face 64 which sealingly receives a valve
plate 65, sealing with surface 64 being provided by a thermally
stable O-ring seal located in a groove 66. The valve plate 65 has a
shallow recess 67 which receives a downwardly deflectable spring
metal planar valve reed 68 which covers four induction
through-passages 69. The reed 68 has an end 70 retained between the
valve plate 65 and the cylinder top end surface 64 and located
laterally in the valve plate by hard metal pins (not shown) in
holes 71. The valve plate also has delivery through-passages 72
located to either side of the induction through-passages covered by
respective deflectable planar metal delivery valve reeds such as 73
retained by arresters such as 74 mounted to the upper surface of
the valve plate 65.
The compressor has a cylinder head 75 which carries dividing walls
and an induction air inlet port 76 and a delivery air outlet port
77. The head also incorporates water cooling channels 78 and 79 and
integral cooling fins 80 within the delivery air flow path. The
cylinder head 65 is bolted with the intermediary of a rubber-coated
metal gasket 71, sealingly and the valve plate 65. In the present
example, long bolts (not shown) extend through the cylinder head,
gasket, valve plate and into cylinder 61 the (not shown) crank case
of the compressor.
In accordance with the invention, the gasket 81 is not entirely
planar as it is formed with three-dimensionally shaped regions 82
and 83 which project upwards into chambers or recesses of cylinder
head 75 which lie in delivery air flow paths from the delivery
valves to the delivery port 77.
As shown, the shaped regions 82 and 83 of the gasket 81 are
interconnected at 84 and 82 has an opening 85 into the respective
delivery air recess of the cylinder head. The shaped regions of the
gasket come into close
proximity with downward projecting internal cooling fins integral
with the cylinder head to assist the distribution of delivery air
flow between cooling surfaces of the fins.
In operation, the compressor functions in a mainly conventional
manner, drawing air during induction strokes via port 76, through
the induction passage past the downwardly deflected valve reed 8
and during compression strokes air under pressure from the
compression chamber of the compressed air passes through delivery
passages 72, and past unseated delivery valve reeds 73 into the
shaped regions 82 and 83 at the lower side of the gasket 81. These
regions thereby provided extended flow pith length for the
delivered air as illustrated by the arrows. By virtue of these
extended flow paths and distribution between cooling fins, air
which is at a relatively high temperature on emerging from the
delivery reed valve is afforded enhanced opportunity to give up
heat to the water cooled walls and internal fins of the cylinder
head before delivery. Such enhanced cooling opportunity is provided
without providing significant added mass or overall physical
dimensions to a compressor.
As the compressor described with reference to FIG. 4 is
liquid-cooled, the gasket may be designed with selectively located
upward projecting regions and apertures which constrain the flow
path of liquid coolant to an extended path, similarly to the
arrangement detailed in the twin cylinder compressor of FIG. 2,
such upward projections performing functions similar to the
recesses 52 of FIG. 2. Alternatively, recesses such as 52 with
which apertures of the gasket cooperate may be provided if
desired.
Of course, the invention may be applied if required to provide
extended flow paths solely of the liquid coolant of a liquid cooled
compressor.
Referring to FIG. 5 of drawings, a single cylinder gas compressor
comprises a crankcase, piston and cylinder which are conventional
and therefore not shown. The present compressor has a valve plate
denoted by reference 91 which carries an annular groove 92 to
contain an O-ring 93 for sealing between the under surface of the
valve plate and the abutting open end face of the cylinder (not
shown). The valve plate has induction air passages 94 in a recessed
area 95 which accommodates a springy flat metal lamina induction
valve reed 96 as disclosed above with reference to FIG. 3a. The
reed 96 is supportable in position between the plate 91 and the
said end face of the cylinder and located in position relative to
the valve plate by hard metal pins (not shown) engaging apertures
97. The valve plate also has delivery passages 98 communicating
with a single delivery reed valve assembly 99 attached to the upper
surface of the valve plate 91. The valve plate is sealingly secured
to the cylinder by bolts (not shown) which secure the liquid cooled
cylinder head 100 and the second sealing means namely between the
valve plate and the cylinder head comprises an intermediate liquid
cooled cooling plate 101 with respective gaskets 102 and 103.
Cooling plate 101 has a central aperture 100a for induction air
flow to the apertures 94. Plate 101 is also of sufficient thickness
to accommodate the delivery reed valve assembly 99 within a recess
region 104 of its under side. This recess communicates with a
further recess region 105 including cooling fins 106 via which
delivery air can flow towards an aperture 107 and through to a
receiving region 108 of the cylinder head communicating with a
further receiving region 109, each receiving region having cooling
fins in the path of delivery air towards the air delivery port 51
of the cylinder head.
In operation of the compressor of FIG. 5, a downward induction
stroke of the piston in the cylinder draws air via induction port
112 of the cylinder head 39 and through central aperture 40a and
passages 94 of the downwardly deflecting induction valve reed 96
into the cylinder. During such induction stroke the delivery reed
valve 99 is of course closed but reopens during the next
compression stroke when air is driven under pressure via the
delivery apertures 98. From the delivery reed valve the delivered
air passes via recesses 104 and 105 of the valve plate and then
upwards via aperture 107 to the interconnected receiving recesses
108 and 109 in turn as shown by the arrows in the upper gasket, on
its way to the delivery port 110.
By virtue of the described arrangement of FIG. 5 wherein all
delivery air passes over internal cooling surfaces of the
compressor over a prolonged time, efficient cooling is achieved
without the substantial additional cost and space required by
external cooling means for delivered compressed air.
Other embodiments and modifications of compressors in accordance
with the invention wherein sealing means between a valve plate and
a cylinder head affords extended fluid flow of delivered air and/or
liquid coolant will now be envisaged by persons skilled in the
art.
* * * * *